Correlation Calculator
Compute the Pearson correlation coefficient from two paired data lists.
What is Correlation?
The Pearson correlation r measures how close two variables are to a straight-line relationship, from −1 (perfectly negatively linear) through 0 (no linear relationship) to +1. It is unitless, which is what makes it comparable across data sets.
How it works
One least-squares pass accumulates the sums of squares and the cross-product, and r is the cross-product divided by the geometric mean of the two sums of squares. Because r only sees a linear pattern, a strong U-shaped relationship can score near zero; the description of strength is paired with that warning.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Realistic sample
Type or paste any realistic input — the tool computes the result locally and instantly.
Common mistakes
Expecting a server round-trip
Nothing is uploaded — every tool in this category runs entirely in your browser.